透明代理：客户端不需要手工在browser中设置代理，减少客户的工作，直接使用nat服务器在firewall规则中指定的代理服务器上网

设置硬件，

nat服务器2块网卡，eth0连接内网，eth1连接adsl拨号，拨号后是ppp0接口

单台squid代理服务器 ip 192.168.0.200

1：iptables

The sar command collect, report, or save UNIX / Linux system activity information. It will save selected counters in the operating system to the /var/log/sa/sadd file.

This is an user contributed article.

This article is a practical step-by-step guide for securing Linux production systems.

Securing your Linux server is important to protect your data, intellectual property, and time, from the hands of crackers (hackers). The system administrator is responsible for security Linux box.

Need to monitor Linux server performance? Try these built-in command and a few add-on tools. Most Linux distributions are equipped with tons of monitoring.

This is one of the key questions many new sys admin ask:

How do I audit file events such as read / write etc? How can I use audit to see who changed a file in Linux?